Field of the Invention
The present invention generally relates to an antenna system and method for installing an antenna system. More particularly, the present invention relates to an antenna system employing a rotatable antenna feed, in particular, a rotatable circularly polarized antenna feed, and a method for installing and operating such an antenna system.
Background Information
As understood in the art, satellite communication systems include a plurality of terrestrially mounted gateways that communicate with one or more orbiting satellites. Each satellite gateway includes an antenna dish, an antenna feed and other types of equipment such a transceiver, amplifiers, waveguides and so on which enable communication between the satellite gateway and one or more of the orbiting satellites. The satellite gateway and a satellite typically communicate with each other over a radio frequency link, such as a Ku-band link, a Ka-band link or any other suitable type of link. For example, the Ku-band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 10 GHz to 18 GHz, and the Ka band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 17 GHz to 40 GHz.
During installation of a gateway, the gateway antenna dish is oriented to align the gateway antenna feed with an antenna feed on an orbiting satellite. Often, the gateway antenna feed and the orbiting antenna feeds are circularly polarized antenna feeds. However, since the polarization of these antenna feeds at the gateway and the orbiting satellite are not perfectly circular and have some elliptical characteristics, the antenna feeds at the gateway and the orbiting satellite often will not be perfectly aligned with each other. This misalignment causes some loss to be present in the communication link between the gateway and orbiting satellite.